all you can do is learn from this experience.. you obviously can't trust one or more of those people ("friends")that were at your place.. who ever did this has something coming back to them so you dont need to worry about revenge. unfortunately this type of thing happens.. the worst part is whoever took it is prolly completely stoned and hasnt realized exactly what he has done to himself. Just make sure next time (if there is) not to get careless w/ valuables.